San Diego Judge Gary Kreep, a conservative legal activist who led a failed fight to challenge President Barack Obama’s citizenship, has been exiled to traffic court after several Superior Court rulings favoring defendants’ constitutional rights.

Kreep, 63, was reassigned Sept. 9 from the downtown San Diego courthouse to a Kearny Mesa facility that handles traffic offenses and small claims.

The move came after prosecutors from the City Attorney’s Office began to boycott his courtroom over his legal approach.

For instance, Kreep often declined to take away a defendant’s 4th Amendment rights against search and seizure — something prosecutors can legally request at various points during the criminal process.

No official reason was given for Kreep’s reassignment. Presiding Judge Robert Trentacosta said through a spokeswoman that the court doesn’t comment on judicial assignments.

Kreep did not respond to numerous requests through the court and by email to comment for this story. San Diego City Attorney Jan Goldsmith also declined to comment on Kreep’s reassignment or what role his office had in it.

On a recent morning in Kearny Mesa Department B, Kreep worked through two dozen traffic cases — speeding, driving on a suspended license, busted taillight, windows too heavily tinted. All of the people appeared without lawyers, which is not uncommon in traffic court.

Most of the Kearny Mesa facility is staffed with court commissioners, who lack the prestige of a judge and are paid $152,00 a year. Superior Court judges, who are elected or appointed by the governor, earn an annual salary of $178,789.

Judges will occasionally fill in for a few days in traffic court, but it’s virtually unheard of to have a Superior Court judge assigned indefinitely to the Kearny Mesa facility.

Apparently Kreep earned the ire only of prosecutors. The Public Defender’s office, which handles the majority of the cases in Kreep’s former courtroom, said its lawyers had no problem with the judge. Private lawyers had the same view.

The reassignment came soon after prosecutors deployed the legal tactic known as a peremptory challenge to keep cases from Kreep’s court, according to defense lawyers and courthouse sources.

Under state law, each side can exert one such challenge to the judge assigned to their case. They don’t have to state a reason. Prosecutors can create a so-called “blanket challenge” by issuing the peremptory challenge for every case assigned to the judge.

“They (prosecutors) are so used to getting their way,” said Heather Boxeth, a criminal defense lawyer who represented many clients in front of Kreep. “But they blanket-challenged him over simple misdemeanors.”

One example was how Kreep handled petty theft cases. Often defendants were given a deferred prosecution deal: plead guilty and in six months — if they had attended classes, not been arrested again, and repaid the store — the pleas would be wiped out.

Kreep would often dismiss these cases long before the six-month period, after the defendant had attended only a session or two, several lawyers said.

He also would release defendants without bail on minor charges if they had a history of showing up at court appearances, Boxeth said. And he was reluctant to impose orders of protection against individuals who had yet to be judged guilty.